Brake



DM.K 2o, 193s. L. E. LA BRE 2,140,752

BRAKE Original Filed April 23. 1931 al? INVENToR. .322, a "m 33 2 3/0340 .ZUDGE/ E f//Q/E" as@ 510 A BY V. A M MTTORNEY Patented ec. 20, 1938UNITED STATES PATENT voI-Flfc'zlz original application April-'23,1931,'seria1 No.

532.265. 1935, Serial No. 24,388

Divided and this application May 31,

13 Claims. (Cl. 18S-152) This' application is a division of my copendingapplication Serial No. 532,265, filed April 23, 1931. The inventionrelates to brakes and is illustrated as embodied in a novel type ofshiftable-anchorage automobile brake.

One feature of the invention relates to arranging for fluid-pressureapplication a brake of the type having a pair of floating orindividuallyshiftable shoes, i. e., arranged to shift individually fromone anchor to another so that both shoes have self-energizingcharacteristics in both directions of drum rotation. Preferably thereare two fluid-pressure operators adjacent the opposite ends of theshoes, and these operators in the form illustrated in themselves embodya number of important features of novelty.

One important object relates to simplifying the wear adjustment of abrake of this type, by utilizing the brake applying cylinders asadjustable (i. e., expansible) anchors instead of attempting to adjustthe shoes. This is especially desirable in combination with afluid-pressure system of the well-known type, now practically universalcommercially, in which a light pressure is maintained in the system evenwhen the brakes are released, as the operating pistons under theiniiuence of this light pressure follow the shoes out automatically asthe anchors are adjusted. As this type of system always includes, in themaster cylinder at the pedal, means for automatically keeping the systemfull of liquid, the adjusted released positions of the pistons areautomatically compensated for in the master cylinder, and the automaticadjustments of the pistons are, therefore, the only adjustments in theentire system,

this not being true of any of the previously-knownl arrangements of wearadjustments for brakes of this type.

An important feature of the invention relates to a simple and effectiveautomatic adjustment for wear capable of embodiment in the wheelcylinders, and to various novel and desirable particular constructionsand arrangements which will be apparent from the following descriptionof the illustrative embodiments shown in the accompanying drawing, inwhich:

Figure 1 is a vertical section through a hydraulic brake of the typedescribed above, just inside the head of the brake drum, showing thebrake shoes in side elevation;`

Figure 2 is a partial section on the line 2-2 of Figure 1, showing theautomatic adjustment device, the brake and the upper valve being shownin brake applied position but the lower valve being 55 shown in tbeposition it assumes when the associated end of the shoe is anchoredwhich also corresponds to brake released position;

Figure 3 is a section, at right angles to Figure 2, on the line 3-3 ofFigure 1; and

Figure 4 is a sectional view on an enlarged scale 6 of one of the valvesVof Figure 2.

In the brake of Figures 1, 2, and 3, there is a. rotatable drum l0, atthe open side of which is a support such as a backing plate I2, andwithin which is arranged the brake friction means which in this casecomprises a pair of floating and individually-shiftable shoes 3|4 and3I6. Return springs 24 are tensioned between the shoes at their oppositeends.

The brake is applied by novel fluid-pressure l0 means, which in thisembodiment includes a pair of hydraulic wheel cylinders 3,26 secured tothe backing plate adjacent each anchorage, and within each of which isarranged a relatively largediameter piston 328 acting on the toe of oneof the shoes (i. e., on the part of the shoe which leaves the anchorageduring forward braking) and a relatively smaller-diameter piston 330acting on the heel of the other shoe (i. e., on the part of the shoewhich remains anchored on forward braking) The pistons may have suitablerubber packing cups 332.

diameter pistons 32B thrust outwardly with more 30 l power than thesmaller-diameter pistons 33t,

with any given uid pressure in the line and in the cylinders 326 betweenthe pistons, the pistons 330 do not operate to shift the heels of theshoes away from their anchors at any time during forward braking. Thusduring forward braking, due to the differential action of the pistonsand the equal action of the return springs, the shoes remaincontinuously anchored instead of leaving the anchors and then comingback with a shock under load.

During reverse braking, the action is the same until'the shoes engagethe drum, whereupon the shoes shift to the opposite anchors under theinfiuence of drum friction, the liquid-filled cylinders serving in amanner analogous to doorL checks to slow up the shifting and minimizeshock. When the brakes are rst applied the plunger formed by the uppervalve 3H) moves forward and the liquid ahead of said plunger forces theplunger 328 outward. However, as the rotation of the drumacts upon theshoe 3 I4, it forces the plunger 328 inward andthe liquid trappedbetween the plunger 328 and the'upper plunger 3io forces the plunger 3|0loutward toits closed position.

V 2 I i The shoes u andv le may be held ylelaingiy m' place by anysuitable spring ysteady rests 48.

The shoes 3I4 and 318 are actuated by pistons 328 of large diameter andpistons 880 of smaller diameter, all arranged in novel wheel cylinderdevices 326l connected bybranches |00 from a union |02 fed by thehydraulic line |04. The pistons are'provided with suitable rubberpacking cups 332, and act with vdiiierential pressures, as previouslydescribed, against the equal tensions of the return springs 24.

The novel wheel .cylinder device 326 contains coaxial cylinders for thetwo pistons 328 and 330, which cylinders are, however, separated by asolid wall |06 and provided with separate inlets |08. The inlets |08 arecontrolled by cone valves 3I0 having stems loosely but guidingly slidinginl passages in plugs 3I2 threaded into the side oi' the wheel cylinderdevice and seated against valve springs 340 which are light enough to beeasily overcome by springs 24. The passages containing the valves are inopen communication with each other through openings 342, and are also inopen communication with conduit |00. The upper valve 3I0 is shownintermediate its brake applied and brake released position while thelower valve is shown in its brake released position. It will beunderstood also that the valves occupy the position oi the lower valvewhen the respectiveshoe end is anchored.

As may be seen more clearly in Figure 4, the passages in the plugs 3|2are formed with two diameters providing a large diameter chamber 3|2aand a small diameter passage 3I2b'. The conical head 3|0a of the valve3I0 is positioned in the chamber 3I2a andthe stem 3|0b is positioned inthe passage 3|2b. 'I'he head 3|0a is the same diameter as the chamber3I2a but the stem 3|0b is smaller than the passage 3I2b to provide anannularpassage for the iiow of uid. However, the stern is large enoughto be guided by the said passage. 'I'he transition between the largediameter chamber and the small diameter passage is formed by a conicalvalve seat 3I2c on which the conical head 3|0a seats in brake releasedor in anchored position. I prefer to make the head 3I0a somewhatcup-shaped and of pliable material such as rubber and it may be securedto the stem 3I0b by being seated in an annular groove formed in the endof the stem. The dimensions of the chamber 3|2a are predetermined sothat the volumes of fluid contained therein are equal to the volumeswhich, when forced into the corresponding cylinder 328 or 330, will movethe respective shoe sufficiently to take up the normal clearance andapply the brake fully.

In operation, brake-applying pressure on the line shiftsthe valves tothe left in Figure 2 until they encounter the end of the chamber 3|2aand this forces the liquid ahead of the valves into the cylinders belowthe pistons, the pistons 328 moving rst because of their greater area.This causes the brake to be applied in the normal case, the shoesanchoring through engagement of pistons 330 with the wall |06 or in theevent that sufllcient liquid has been trapped in the cylinder anchoringthrough the trapped liquid upon said wall |08.

If, however, the brake has worn so that it is not fully applied when thevalves 3 l0 reach their left-hand positions, additional liquid can owpast the valves, around their loosely-iltting stems and past theirflexible heads which may be deformed adjacent the passage |08 by thepressure of thefluid, into the cylinders to cause i'ull application ofthe brake. When the brake is now lagain released, valves l|0 move to theright until they seat withdrawing from the cylinders an amount of liquidequal to the volume of the cham- -ber 3|2a,.whereupon the additionalliquid so in-- troduced is trapped in the cylinders and holds the shoesin automatically adjusted positions with predetermined clearance withrespect to the drum, and the shoes; anchor throughthe pistons on thetrapped fluid. As explained above, the master cylinder at the pedalautomatically forces more liquid into the system to replace that trappedin the wheel cylinders. The above-described adjustment introduces theadditional liquid behind pistons 328 if it takes place during forwardbraking, and behind pistons 330 if it takes place during reversebraking.

It will be understood that the springs 340 serve to overcome thefriction of movement of the valve 3I0 and thereby prevent any-pressuredifferential arising irom sudden application of the brakes from forcingfluid past the valve before it encounters the end of chamber 3|2a andthereby causing adjustment when it isvunnecessary.

While an illustrative embodiment has been described in detail, it is notmy intention to limit the scope of the invention to this particularembodiment, or otherwise than by the terms of the appended claims.

I claim:

1. A brake comprising a pair of shoes, two uid pressure applying devicesacting on said shoes, said shoes anchoring on said applying device inbraking and means for trapping fluid in said devices through which theanchoring torque of the shoes is transmitted to said devices.

2. A brake comprising a pair of shoes, two uid pressure applying devicesacting on said shoes, each applying device being formed with a centralpartition, acting on said shoes and also serving as an anchor for theshoes.

3. Brakes comprising a pair of shoes, a pair of fluid pressure cylinderspositioned between adjacent ends of said shoes, a piston in each of saidcylinders for applying said shoes, projections on the inner ends of thepistons, and means formed as parts of said cylinders with which saidprojections contact to take the braking torque from the shoes throughthe pistons.

4. Brakes comprising a drum, a pair of shoes, a pair of fluid pressuredevices each including a cylinder positioned between said shoes andserving to apply said shoes to the drum, elements interposed between theiiuid pressure devices and the shoes for transmitting brake applyingforce, and means formed as parts of said cylinders comprising partitionswith which said elements contact to take the braking torque from theshoes through the elements.

5. A brake comprising a pair of shoes, two fluid pressure applyingdevices acting on the shoes and also serving as anchors therefor, andautomatically acting valves embodied in said devices and trappingtherein quantities of fluid compensating for Wear of the brake, saidvalves having springs urging them inthe brake applying direction andsaid shoes having springs urging them in the brake releasing positionand strong enough to overcome said valve springs.

6. A brake comprising a pair of shoes, two fluid f ing springs urgingthem in the brake applying direction and said shoes having springsurging them in the brake releasing position and strong enough toovercome said valve springs.

'7. A brake comprising a drum,a pair of shoes each arranged to anchor onone end in one direction'of rotation of the drum and on the other end inthe other direction of rotation of said drum, a pair of applying deviceseach positioned between adjacent ends of said shoes and each arranged totake the anchoring torque and each applying device comprising coaxialcylinders containing operating pistons and separated by a solid wall andhaving means to trap fluid between the pistons and said wall to positionthe pistons positively in their inner positions.

8. A cylinder member for a brake applying device comprising coaxialcylinders of dierent diameters separated by a solid wall, and having avalve controlled inlet to each of said cylinders, together with a commonsource of uid pressure for the two inlets.

9. A brake comprising a pair of shoes, two uld pressure applying devicesacting on said shoes each formed with a central partition, and means fortrapping fluid in said devices through which fluid the shoes may anchoron said partition in braking. 1

10. A brake comprising a pair of shoes, two iuid pressure applyingdevices each formed with a central partition, acting on said shoes andalso serving as anchors therefor, and each positioned at an oppositeside of the brake from the other, means for supplying uid to saiddevices for applying the brakes, and means for trapping iluid in saiddevices through which iiuid the shoes may A anchor on said partition inbraking.

11. vA brake comprising a pair of shoes, two

fluid pressure applying devices acting on said' shoes and on which saidshoes anchor in braking and which are positioned between said shoes atopposite sides of said brake, means for supplying fluid to said devicesfor applying said shoes, and means for trapping fluid in said devicesthrough which uid the shoes may anchor on said devices.

12. A brake comprising a pair of shoes each arranged to anchor at anopposite end depending upon the direction of rotation of the drum, twofluid pressure applying devices acting on the shoes and also serving asanchors therefor, each positioned at an opposite side of the drum fromthe other between adjacent ends of the two shoes, and automaticallyacting valves which are embodied in said devices and which are arrangedto trap therein quantities of uid through which trapped fluid the shoesmay anchor on said devices during braking, the trapping oi the uidcompensating for wear of the brake.

13. A brake comprising a pair of shoes, two uid pressure applyingdevices acting on said shoes and forming anchors for said shoes, andautomatically acting valves which are embodied in said devices, andwhich trap therein quantities of fluid to compensate for wear of thebrakes, said valves comprising plungers which move a predetermineddistance to discharge a measured amount of iiuid into said devices andsprings acting on the plungers in a direction tending to move them inthe brake applying direction.

LUDGER E. LA BRIE.

